Characterizing the Semantic Web on the Web

Abstract

Abstract. Semantic Web languages are being used to represent, encode and exchange semantic data in many contexts beyond the Web -in databases, multiagent systems, mobile computing, and ad hoc networking environments. The core paradigm, however, remains what we call the Web aspect of the Semantic Web -its use by independent and distributed agents who publish and consume data on the World Wide Web. To better understand this central use case, we have harvested and analyzed a collection of Semantic Web documents from an estimated ten million available on the Web. Using a corpus of more than 1.7 million documents comprising over 300 million RDF triples, we describe a number of global metrics, properties and usage patterns. Most of the metrics, such as the size of Semantic Web documents and the use frequency of Semantic Web terms, were found to follow a power law distribution.

Compact Representation of Large RDF Data Sets for Publishing and Exchange

“…Regarding the structure of RDF real-world data, several studies point to the presence of power-law distribution, in term frequencies [10], resources [19] and schemas [21].…”

“…Ding and Finn [10] reveal that Semantic Web graphs fit power-law distribution within some metrics such as the size of documents and term frequency use; most terms are described through few triples. Regarding the use of an RDF schema (RDFS [5]), the space of instances is sparsely populated, since most classes and properties have never been instantiated.…”

“…-Billion Triples Challenge: One of the largest RDF data sets (∼3.2 billion statements) available at the moment of writing, given as part of the Semantic Web Challenge 10 . Data is collected from Sindice, Swoogle, DBpedia and others.…”

“…In particular, we introduce a new representation format (Header-DictionaryTriples: HDT) that modularizes the data and uses the skewed structure of big RDF graphs [10,19,21] to achieve large spatial savings. It is based on three main components: -A header, including logical and physical metadata describing the RDF data set.…”

On the Ostensibly Silent ‘W’ in OWL 2 RL

“…The core of these technologies is the Resource Description Framework (RDF) for publishing data in a machine-readable format, wherein there now exist millions of RDF data sources on the Web contributing billions of statements [9]. The Semantic Web technology stack also includes means to supplement instance (assertional) data being published in RDF with ontologies described in RDF Schema (RDFS) [3] and the Web Ontology Language (OWL) [23] (terminological data) providing machines a more sapient understanding of the information -in particular enabling deductive reasoning to be performed.…”